 /* class 类选择器 */
 .ji {
    color: red;
}

/* id选择器 */
#hui {
    color: yellow;
}

.zhi {
    padding-left: 100px;
}

/* 标签选择器
    <div>{font-size="100px"} */
/* 组合选择器 */
.ji,
#hui {
    font-style: italic;
}

/* 空格选择器 选择子元素 */
.done li {
    color: gray;
    text-decoration: line-through;
}

.todo li {
    width: 170px;
    height: 30px;
    position: relative;
}

/* .todo li button{
    float: right;
} */
.todo li button {
    position: absolute;
    top: 0;
    right: 0;
}
.pre{
    cursor: not-allowed;
}
.active{
    text-decoration: underline;
}
.box{
    width: 0px;
    height: 0px;
    background-color: blueviolet;
    /* padding: 10px; */
    border-left: 50px solid brown;
    border-top: 50px solid white;
    border-bottom: 50px solid white;
    border-right: 50px solid white;
    margin: 40px;
    box-sizing: content-box;
    /* width: 0;
    height: 0;
    border-top: 100px solid red;
    border-left: 100px solid transparent; */
}


.box2{
    width: 100px;
    height: 100px;
    background-color: red;
    border: 10px solid red;
    border-radius: 50%;
}
